The present invention relates to a damping device and particularly one for use in connection with vehicle accessory doors.
In recent years, vehicles have included a variety of storage compartments for the convenient storage of relatively small items such as garage door openers, sunglasses, and the like. Many of these items are stored in overhead storage compartments which are centrally located in the roof area of the vehicle and which include pivot down doors. In some cases the doors integrally include pockets for receiving sunglasses or other small personal items. In order to control the movement of such doors, frequently, viscous damping devices have been employed. One popular damping device is a housing filled with a viscous damping fluid such as a silicone, in which a paddle wheel on an axle is mounted with the axle extending outwardly, terminating in an external gear. The housing is typically secured to the side of the storage compartment while a gear on the pivoted door engages the gear on the axle of the viscous damping device to slow the lowering of the door once a push button latch releases the door. For heavier doors, a pair of such viscous damping devices are used on opposite ends of the pivotally mounted door.
Although these systems provide the desired action under reasonable temperature ranges, during extreme temperatures the viscous damping devices tend to change characteristics due to the viscous damping medium changing its viscosity. As a result, these conventional viscous damping devices, which are somewhat expensive and include a relatively large number of parts, do not always function satisfactorily over temperature extremes encountered in the automotive environment.
Recently, a proposed viscous damping device has included a temperature compensating cup mounted within the viscous damping chamber to maintain the "drag" of the viscous damping device relatively constant with change in temperature. U.S. patent application Ser. No. 07/840,340 filed on Feb. 24, 1992 and entitled TEMPERATURE COMPENSATED ROTARY DAMPER discloses such a device. Although this device provides improved performance, it nonetheless utilizes a viscous damping fluid in a sealed chamber which adds to the cost and complexity of the structure.